According to the Fair Use provision of the copyright Act, to determine whether the use made of a work in any particular case is fair use, the following factors must be considered:

	The purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
	The nature of the copyrighted work;
	The amount and substantiality of the portion used in relation to the copyrighted work as a whole;
	The effect of the use upon the potential market for or value of the copyrighted work;

For further information, explore this site with information on Fair Use.